Pumping System And A Method For Pumping Fluids

ABSTRACT

The invention relates to a pumping system ( 3 ) for pumping fluid. The pumping system ( 3 ) comprises a first pumping unit ( 1 ) comprising a first flow path ( 4 ) and a second pumping unit ( 2 ) comprising a second flow path ( 5 ). The fluid pumped by the first pumping unit ( 4 ) is guided through the first flow path ( 4 ), and the fluid pumped by the second pumping unit ( 2 ) is guided through the second flow path ( 5 ). The first pumping unit ( 1 ) and the second pumping unit ( 2 ) are functionally coupled. The first flow path ( 4 ) and the second flow path ( 5 ) are adapted to be functionally independent from each other.

FIELD OF THE INVENTION

The invention relates to a pumping system and a method for pumping fluid as well as to a use of a pumping system.

BACKGROUND OF THE INVENTION

In the well oil production, several diverse techniques of pumps are used today. Positive displacement pumps, according to the principle of Moineau, have been successfully used in the oil well production for decades. Special application thereby is the production of heavy oil and oils with some fine content.

The positive displacement pumps are also called progressive cavity pumps. The conventional progressive cavity pumps comprise a helical shaft as rotor that rotates in a stator. The pump operation is based on the positive displacement theory. Liquid is displaced from the stator, in particular an elastomeric stator, by rotation of the helical shaft. A rotor may be of various construction forms which allow some flexibility in terms of volumes and production head which governs the maximum differential pressure at the pump in order to define the maximum allowable depth.

U.S. Pat. No. 5,820,354 discloses a cascaded progressing cavity pump system wherein at least two progressive cavity pumps are connected in series. The flow volume rate of the second pump or pump section is less than the flow volume rate of the first pump or pump section. The cascade arrangement of progressing cavity pumps may be achieved by interconnecting end-to-end separate pump assemblies. A cascade arrangement of progressing cavity pump sections can be achieved by the attachment of the rotor/stator pairs of each pump section in series with suitable universal mechanisms and housings.

DE 24 18 967 discloses a progressive cavity pump, wherein the rotor is divided in rotor elements that define sections in which different media of fluids may be injected and thus were mixed together by the rotation of the rotor elements.

DE 1 728 143 discloses a progressive cavity pump comprising two injection openings so that fluid can be pumped by a rotor and thus be mixed together.

OBJECT AND SUMMARY OF THE INVENTION

It is an object of the invention to provide a pumping system with an increased system stability and reliability.

In order to achieve the object defined above, a pumping system and a method for pumping fluids as well as a method of using of the pumping system for pumping fluid according to the independent claims are provided.

According to a first exemplary embodiment of the invention, a pumping system (or a pumping arrangement) for pumping fluid is provided. The pumping system comprises a first pumping unit comprising a first flow path (along which, in an embodiment, the fluid is pumpable from a source to a first destination) and a second pumping unit comprising a second flow path (along which, in an embodiment, the fluid is pumpable from the source to a second destination which may be the same as the first destination). Fluid is pumped by the first pumping unit and is guided through (or along) the first flow path. The fluid pumped by the second pumping unit is guided through (or along) the second flow path. The first pumping unit and the second pumping unit are functionally coupled (for instance, the first pumping unit and the second pumping unit may share a task and/or a common resource, such as a drive unit, required to operate the first pumping unit and the second pumping unit) wherein the first flow path and the second flow path are adapted to be functionally independent from each other (for instance, it may be possible to operate the first pumping unit and the second pumping unit independently from one another, for instance use the first pumping unit without using the second pumping unit, use the second pumping unit without using the first pumping unit, or using both pumping units at the same time).

According to a further exemplary embodiment, a method for pumping fluid is provided. Fluid pumped by a first pumping unit is guided through a first flow path, whereas fluid pumped by a second pumping unit is guided through a second flow path. The first pumping unit and the second pumping unit are functionally coupled, wherein the first flow path and the second flow path are provided functionally independent from each other.

According to a further exemplary embodiment, a use of or a method of using the above-mentioned pumping system is provided in one of the fields of drainage purposes, oil production, water catchment and/or geothermic systems.

The term “functionally coupled” may define an interaction of two elements, namely the first pumping unit and the second pumping unit. By the term “functionally coupled”, it may be expressed that the first and the second pumping unit may interact in such a way that the first pumping unit and the second pumping unit are for instance driven by one and the same driving power, have one and the same suction point, are coupled mechanically together, are attached together or form an integrated cooperating pumping system. Additionally, the term “functionally coupled” may define that the pumping units are being fed directly or indirectly by the same fluid reservoir or fluid source, such as the oil field, or the same sucking point or suction side. Further on, the term “functionally coupled” may define one or a plurality of functional coupled interactions of the first or the second pumping unit.

The term “suction point” defines a source or a location or a point of a fluid reservoir, such as an oil field, where a pump extracts the fluid from the fluid reservoir. By the term “comprising a common suction point” it may be meant that the first pumping unit and the second pumping unit extract the fluid from the fluid reservoir from one and the same location, respectively suction point.

The term “flow path” may describe the way of a pumped fluid starting from the fluid reservoir to the pump unit, the way through the pump unit, as well the way from the pump unit away, such as outside to a storage reservoir of the fluid, for example.

The term “functionally independent” may describe two systems that are functionally decoupled from one another. This means for example that the first flow path and the second flow path do not necessarily have to be activated at the same time to enable fluid pumping (for instance for oil production), or that the first flow path and the second flow path have no common parameters that influence each other. For instance, the pressure, the temperature, the flow rates or the flow velocity may be different between the first flow path and the second flow path. Additionally, if one of the parameters, such as the flow pressure is changed, this will not affect the other flow path. In other words, if one of the first flow path or the second flow path fluid will be blocked the other flow path may still pump fluid.

With an embodiment of the present invention, a pumping system is provided that lowers the failure probability. With the invention two, three or any other plurality of pumping units may be attached and be brought in functional contact with each other, for instance by being powered by one common power system. Since the flow path of different pumping units are functionally independent from each other, even if one of the pumping units fails, the whole pumping system may still be able to pump further fluid through the fluid path of the working pumping unit.

In conventional pumping systems, a plurality of pumping units may share one and the same flow path of the fluid, so that if one of the pumping units fails this will affect the working pumping unit. The fluid that flows in the flow path may be blocked by the failing pump, so that even the working pumping unit is not able to pump further fluid. With other words, the failing pumping unit blocks the fluid flow in this flow path so that the whole pumping system is not longer able to pump further fluid.

In an embodiment of the present invention, the pumping units are functionally coupled in one pumping system but each pumping unit comprises its dedicated flow path that is functionally decoupled and independent form the other(s), so that a blocking of a flow path due to a failing pumping unit may be prevented by an embodiment of the present invention. Thus, the failure probability is lowered and the reliability of the whole system is raised because even if one pumping unit fails the whole pumping system is still able to pump further fluid.

In an embodiment, several pumps may be connected mechanically in a serial manner (for instance may be vertically stacked in a bore hole), but may have parallel connected fluidic paths. This architecture allows for both a space saving arrangement of the pumps and a proper functioning of the pumps even when a part thereof fails.

According to a further exemplary embodiment, the pumping system further comprises a drive unit such as a prime mover. The first pumping unit and the second pumping unit are functionally coupled such that the prime mover is adapted for driving the first pumping unit and the second pumping unit. According to the exemplary embodiment, the functional coupling of the first and the second pumping unit is realized by providing one driving mechanism for both pumping units. Thus, a shared driving mechanism, respectively a prime mover, for each pumping unit may be unnecessary so that maintenance costs and energy consumption may be reduced.

According to a further exemplary embodiment, the prime mover is attached to at least one of the first pumping units and the second pumping units. The prime mover may comprise combustion engines, electric engines and/or hydraulic motors. Thus, the prime mover has not necessarily been placed on the surface outside of the drill hole. The whole pumping system may be produced as compact pumping system which can be mounted in one piece in a drilling hole. Further connections to other external equipments may be unnecessary. Therefore, the whole pumping system may be provided as a small, self-sufficient and complete unit. Thus, the installation of the pumping system as well as the transportation may be simplified. Further on, due to the direct connection of the prime mover to the pumping units, energy or respectively driving energy may be transmitted without a loss of energy due to short transmission distances.

According to a further exemplary embodiment, the pumping system comprises a force transmitting element. The force transmitting element is adapted for transmitting a driving power to the first pumping unit and/or the second pumping unit. According to the present embodiment, a force transmitting element may transmit the driving power such as a driving force or a driving torque from the driving units or the prime mover to the pumping units over a long distance. Thus, the location of the prime mover is not restricted by space restrictions or other restrictions at the installation or working point of the pumping units. The prime mover may be placed on the surface outside of the drilling hole, whereas the pumping units may be installed to a pumping region close to the oil/fuel reservoir. The distance between the pumping units and the prime mover is bridged by the force transmitting element. The force transmitting element may comprise a sucker rod string, a tension rope or a belt, for instance. Thus, the prime mover does not raise the installation dimensions of the pumping system in the drilling hole. Thus, the pumping units of the pumping system may even be installed in small drilling holes with a small diameter. Further on, if the prime mover is defect, the pumping units may be kept in the drilling hole and only the defect prime mover may be exchanged and repaired, such that it may be not necessary to dismount the pumping units itself. Maintenance time may thus be reduced.

According to a further exemplary embodiment, the pumping system further comprises a rod element. The rod element is adapted for functionally coupling the first pumping unit and the second pumping unit such that a driving torque is transmitted from the first pumping unit to the second pumping unit. By the present exemplary embodiment, the functional coupling of the first and the second pumping unit is provided by the rod element. If the driving torque from the prime mover is transmitted to the first pumping unit, the rod passes down the driving torque to the second pumping unit. Thus, the first pumping unit and the second pumping unit need not have to be attached in direct contact with each other. Each of the pumping units may be located in a certain distance and may be functionally coupled by the rod. Thus, since the first pumping unit and the second pumping unit may not have to be in direct contact, more space for designing the location of the flow paths and the pumping units itself is provided, for instance. Further on, since the pumping units may be installed in a certain distance from one another, overheating problems may be reduced, because the excessive heat may be discharged easier.

According to a further exemplary embodiment, the rod element comprises an auxiliary conduit. The auxiliary conduit is adapted for connecting a suction side and the first flow path.

The term “suction side” may denote the location of the pumping system that is closest to the fluid reservoir from which fluid is pumped by the pumping units. In other words, the suction side may be the contact side from one of the pumping units with the fluid.

By the exemplary embodiment, for instance the second pumping unit comprises the suction side and is thus closest to or in contact with the fluid so that a pumping of the fluid is possible. On the other side, the first pumping unit may be located (in a drill hole vertically) above the second pumping unit, so that no direct contact with the fluid reservoir is present. Therefore, the auxiliary conduit connects the fuel reservoir respectively the fluid source with the first pumping unit and thereby enabling the first flow path to get in contact with the fluid reservoir. Thus, even if one of the pumping units is not in direct contact with the fluid reservoir, a pumping with a first and a second pumping unit may be still possible.

According to a further exemplary embodiment, the first pumping unit is adapted to be fed by fluid transported in the auxiliary conduit, wherein the second pumping unit is adapted to be fed by fluid directly of the suction side.

Thus, the auxiliary conduit may be designed to pass the second pumping unit by a feedthrough through the second pumping unit or may also surround the second pumping unit. Further on, the auxiliary conduit may be integrated in the rod element.

According to a further exemplary embodiment, the auxiliary conduit is formed within the second pumping unit. In other words, the auxiliary conduit may be integrated in the second pumping unit. Thus, weight for further conduit parts may be reduced.

According to a further exemplary embodiment, the pumping system further comprises an inner tubing. The first pumping unit and the second pumping unit may be located within the inner tubing. The first pumping unit may be located downstream the second pumping unit in a flow pumping direction, or vice versa.

The term “fluid pumping direction” may denote the direction of the fluid pumped by the pumping unit from the fluid reservoir to a desired location. In other words, the first and the second pumping unit may be stacked vertically in a bore hole, for instance. The first and the second pumping unit may be—mechanically—connected in series, wherein the first and the second fluid paths may be connected in parallel.

If the first and the second pumping units are located in an inner tubing, an integration in a drill hole of the pumping system may be simplified. It is not longer necessary to install each pumping unit separately. For instance, the inner tubing may be installed in one piece into the drilling hole and thus the pumping units.

Further on, the inner tubing may comprise inner sealings that seal automatically the inner tubing with surrounding installations, for instance the drilling hole. Thus, a simplified installation may be possible if the pumping units are pre-installed in the inner tubing.

According to a further exemplary embodiment, the pumping system further comprises an outer tubing. The inner tubing is thereby located within the outer tubing, wherein the inner tubing is spaced with respect to the outer tubing for providing a fluid drain (i.e. a conduct via which the pumped fluid may be filled into a storage container) there between. Thus, the pumping system may be flexibly adjusted to a varying inner diameter of a drilling hole in an easy way. The outer tubing may consist of a flexible material and may thus be adapted to flexibly match to contours of an inner surface of the drilling hole. The inner tubing including the pumping units may be in a standardized and preinstalled environment and may be installed and connected to the outer tubing. Thus, if the outer tubing comprises already defined connection elements, an easy connection to the inner tubing may be possible, because the installation elements may not be installed one by one to the drilling hole but may be preinstalled to the outer tubing.

According to a further exemplary embodiment, the first flow path or the second flow path may be partially located in the fluid drain. The fluid drain between the inner tubing and the outer tubing may be used for guiding fluid outside of the bore hole. Thus, the second flow path of the second pumping unit may be guided after being pumped by the second pumping unit outside of the inner tubing in the fluid drain, such as an annulus, whereas the first flow path is still located in the inner tubing until the fluid exits the drilling hole. Thus, by using the fluid drain and the inner tubing as flow paths, a separation of the first flow path and the second flow path may be provided. Complex installations, that combine the first flow path of the first pumping unit and the second flow path of the second pumping unit both in the inner tubing may not be necessary due to the guiding of one flow path in the fluid drain. Thus, costs for complex designs and rising maintenance time of such a complex design may be prevented and reduced.

According to a further exemplary embodiment, the pumping system further comprises a barrier element. The barrier element is located in the inner tubing between the first pumping unit and the second pumping unit. The barrier element is adapted for separating the first flow path and the second flow path. By the installation of the barrier element in the inner tubing, an easy way of separating both flow paths is provided. For instance, the barrier elements may be installed in the inner tubing behind the second pumping unit in flow direction and may thus guide the pumped fluid from the second pumping unit outside of the inner tubing to the fluid drain. Thus, a part of the second flow path is guided outside of the inner tubing to the fluid drain and further on outside of the drilling hole without any complex installations or further tubings. The barrier element may be adapted for providing a passage for the first flow path to the first pumping unit. This may be realized by the auxiliary conduit that is connecting the suction side, respectively the fluid reservoir, with the passage of the barrier element. Thus, in simple way a separation of the first and the second flow path is provided.

According to a further exemplary embodiment, the pumping system further comprises a sealing element. The sealing element is adapted for spacing the inner tubing and the outer tubing. Further on, the sealing element is adapted for preventing a flow of the fluid against the fluid pumping direction in the fluid drain. The sealing element in the fluid drain may fulfil two functions, the first function is to space apart the inner tubing from the outer tubing, and the second function is to prevent a flow back of the pumped fluid. Thus, it is not necessary to use a sealing element on the one side and a flow control element on the other side. According to an embodiment of the present invention, only one part for both functions may be provided so that system complexity may be reduced.

According to a further exemplary embodiment, at least one of the first pumping unit and the second pumping unit comprises a progressive cavity pump with a rotor element, such as a helical shaft, and a stator element. Thus, the pump operation may be based on the positive displacement theory, also named as Moineau principle. Liquid may be displaced from the stator by a rotation of a metal helical rotor shaft. The rotor may be of various construction which allows for some flexibility in terms of volumes and production head which governs the maximum differential pressure at the pump. The rotor is rolled around the inside surface of the stator whereby the form of the motion of the rotor gives rise to the curves called hypocycloids. In order to produce an effective seal between the rotor and the stator, the rotor may be formed in a circular cross-section and the stator in an oval one. Thus, the rotor takes a form similar to a core screw.

According to a further exemplary embodiment, the rotor element, respectively the helical shaft, is hollow for connecting the suction side and at least one of the first flow path or the second flow path. With other words, the rotor elements may adopt the functions of the auxiliary conduit in order to guide for instance the first flow path through the second pumping unit. Thus, the rotation element may adopt a plurality of functions so that further installations, for instance the auxiliary conduit, are no longer necessary. Thus, system complexity and maintenance costs may be reduced.

According to a further exemplary embodiment, the pumping system further comprises a gear element which may act as some kind of switch. The gear element is adapted for selectively driving exclusively one or both of the first pumping unit and the second driving unit. Thus, it may be possible to drive only one pumping unit, whereas the other pumping unit may be repaired, for instance. The gear element may selectively couple or decouple for instance the force transmitting element or the rod, in order to selectively drive the first or the second pumping unit.

Further on, in a further exemplary embodiment, also a plurality of three or more pumping units may be provided, whereby each pumping unit is functionally coupled to each other, whereas each flow paths of the plurality of pumping units are functionally independent from each other.

The exemplary embodiments for the pumping system may also be provided to the method and the method of use, and vice versa.

An embodiment of the invention may be basically composed of two progressive cavity pumps attached to each other and powered together by the prime mover from the surface via a sucker rod string or directly in the drilling hole by an electric or hydraulic motor.

Both pumping units may have a common suction point, however, the flow path may be individually and fully independent from each other. The flow path from the lower pumping unit, for instance the second pumping unit, is diverted from the other flow path from the upper pump, for instance the first pumping unit. The flow path of the lower pumping unit may be guided through the fluid drain and the production from the upper pumping unit, for instance the first pumping unit, flow straight ahead through the tubing string respectively the inner tubing.

Thus, the production may be doubled by the installation of a pumping system according to the present invention. Since both fluid paths are fully independent from each other, production is ongoing even one pump fails or the tubing string is leaking.

The term “fluid” may denote any liquid and/or gaseous substance, optionally comprising also solid particles.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in more detail hereinafter with reference to the examples of the embodiment but to which the invention is not limited:

FIG. 1 illustrates a progressive cavity pump;

FIG. 2 illustrates a schematical view of a dual progressive cavity pumping system according to an exemplary embodiment of the present invention.

DESCRIPTION OF THE EMBODIMENTS

The illustrations in the drawings are schematical. In different drawings similar or identical elements are provided with the same reference signs.

FIG. 2 illustrates an exemplary embodiment according to the present invention. The pumping system 3 comprises a first pumping unit 1 with a first flow path 4 and a second pumping unit 2 with a second flow path 5. The fluid pumped by the first pumping unit 1 is guided through the first flow path 4 and the fluid pumped by the second pumping unit 2 is guided through the second flow path 5. The first pumping unit 1 and the second pumping unit 2 are functionally coupled. The first flow path 4 and the second flow path 5 are adapted to be functionally independent from each other.

FIG. 1 illustrates a conventional progressive cavity pump. The pump comprises a rotor element 16 and a stator element 17. The rotor element 16 has a helical curved shape wherein the stator 5 comprises a helically inner shape. Due to the rotation of the rotor 16, fluid may be pumped due to moving cavities between the stator 17 and the rotor element 16. The rotor element 16 is driven by a prime mover 6 wherein the driving torque may be transmitted by a force transmitting element 7. The rotor element 16 ends at a suction point SP in the bore hole. The suction point SP defines the point where the pump is pumping away the fluid from the fluid reservoir.

FIG. 2 shows an exemplary embodiment of the present invention. The pumping system 3 comprises a first pumping unit 1 and a second pumping unit 2. The first pumping unit 1 is located above the second pumping unit 2 in a fluid pumping direction. The fluid pumping direction is illustrated by the arrows in FIG. 2. The first pumping unit 1 is pumping fluid through a first flow path 4 that is outlined by the bold arrows. The second pumping unit 2 is pumping fluid through the second flow path 5 that is outlined by the white arrows. As illustrated in FIG. 2, the first flow path 4 and the second flow path 5 are functionally independent and are decoupled from each other. Nevertheless, both the first flow path 4 and the second flow path 5 have the same suction side 9, which means that both the first pumping unit 1 and the second pumping unit 2 pump fluid from the same position of the same fluid reservoir.

In the illustrated exemplary embodiment of FIG. 2, the second pumping unit 2 pumps the fluid from the suction side 9 in a fluid pumping direction. The second flow path 5 defines the way starting from the suction side 9 through the second pumping unit 2. Afterwards, the second flow path 5 is guided outside an inner tubing 10 of the pumping system 3. The first pumping unit 1 as well as the second pumping unit 2 may be located in the inner tubing 10. Thus, in order to functionally decouple the first flow path 4 and the second flow path 5, either the second flow path 5 has to be guided through the first pumping unit 1 or has to be guided outside of the inner tubing 10 in order to separate the flow paths 4, 5. As shown in FIG. 2, the second flow path 5 is guided outside of the inner tubing 10. Therefore, an outer tubing 11 is provided that is spaced with regard to the inner tubing 10 to provide a fluid drain 12. In order to define or delimit the fluid drain, such as an annulus 12, sealing elements 14 may be inserted to provide a defined distance between the outer tubing 11 and the inner tubing 10. In fluid pumping direction (see arrows 5) downstream of the second pumping unit 2 a connection is made from the inner tubing 10 to the outer tubing 11, so that the second flow path 5 is guided outside of the inner tubing 10 to the fluid drain 12 and from there to a container (not shown). The first pumping unit 1 and the second pumping unit 2 are located in a borehole and may be located vertically one upon the other. The first pumping unit 1 and the second pumping unit 2 are thus mechanically coupled in series, for instance.

Further on, the first flow path 4 is guided from the suction side 9 through the second pumping unit 2 to the first pumping unit 1. Therefore, a rod element 8 which is hollow according to the exemplary embodiment of FIG. 2 provides a connection between the suction side 9 and the first pumping unit 1 in order to enable the first flow path 4 to the first pumping unit 1. With other words, the first flow path 4 and the second flow path 5 may be parallel fluid connections. Thus, the first flow path 4 and the second flow path 5 are functionally decoupled from each other and may be operable independently.

Further on, the auxiliary conduit, respectively the rod element 8 may provide a couple of functions. Firstly, the rod element 8 may transmit a driving torque from the first pumping unit 1 to the second pumping unit 2. The auxiliary conduit, or respectively the rod element 8 including the auxiliary conduit, may at the same time provide the first flow path 4 and thus a connection between the suction side 9 and the first pumping unit 1 without getting in functional contact with the second flow path 5.

In order to improve the control of the first flow path 4 and the second flow path 5 a barrier element 13 may be installed in the inner tubing 10 between the first pumping unit 1 and the second pumping unit 2. As shown in FIG. 2, the rod element 8 may be guided from the suction side 9 through the second pumping unit 2 and the barrier element 13, such that the first flow path 4 may be guided directly to the first pumping unit 1. By the use of the barrier element 13, an easy and effective separation of both flow paths 4, 5 may be provided. If one of the fluid pumping units 1, 2 is defect, this would not affect the fluid path 4 or 5 of the working pumping units 1, 2.

The pumping units 1, 2 may be driven by separately attached motor units, such as hydraulic, combustion or electric motors. Besides, the pumping units 1, 2 may be driven by a common prime mover 6 that may either be located directly at one of the pumping units 1, 2 or on a surface outside of the drilling hole. The driving torque may be transmitted by a force transmitting element 7 to either the first pumping unit 1 or the second pumping unit 2, whereas the force transmitting element may be further transmitted to the other pumping unit 1, 2 by the rod element 8.

The first pumping unit 1 and the second pumping unit 2 may comprise a progressive cavity pump with a rotor element 16 and a stator element 17 which is shown in FIG. 2. The stator element 17 may be attached to a housing 18. The housing 18 of the first pumping unit 1 and the second pumping unit 2 may be either directly attached to the inner tubing 10 or may be attached to the inner tubing by a spacing element respectively an inner sealing 15.

Finally, it should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be capable of designing many alternative embodiments without departing from the scope of the invention as defined by the appended claims. In the claims, any reference signs placed in parentheses shall not be construed as limiting the claims. The words “comprising” and “comprises”, and the like, do not exclude the presence of elements or steps other than those listed in any claim or the specification as a whole. The singular reference of an element does not exclude the plural reference of such elements and vice-versa. In a device claim enumerating several means, several of these means may be embodied by one and the same item of software or hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

LIST OF REFERENCE SIGNS

-   1 first pumping unit -   2 second pumping unit -   3 pumping system -   4 first flow path -   5 second flow path -   6 prime mover -   7 force transmitting element -   8 rod element -   9 suction side -   10 inner tubing -   11 outer tubing -   12 fluid drain -   13 barrier element -   14 sealing element -   15 inner sealing -   16 rotor element -   17 stator element -   18 housing -   SP suction point 

1. A pumping system for pumping fluid, wherein the pumping system comprises: a first pumping unit comprising a first flow path; and a second pumping unit comprising a second flow path; wherein fluid pumped by the first pumping unit is guided through the first flow path; wherein fluid pumped by the second pumping unit is guided through the second flow path; wherein the first pumping unit and the second pumping unit are functionally coupled; and wherein the first flow path and the second flow path are adapted to be functionally independent from each other, wherein at least one of the first pumping unit and the second pumping unit comprises a progressive cavity pump.
 2. The pumping system of claim 1, further comprising: a drive unit, particularly a prime mover; wherein the first pumping unit and the second pumping unit are functionally coupled such that the drive unit is adapted for driving the first pumping unit and the second pumping unit.
 3. The pumping system of claim 2, wherein the drive unit is attached to at least one of the first pumping unit and the second pumping unit; wherein the drive unit is selected from one of the group consisting of a combustion engine, an electric engine and a hydraulic motor.
 4. The pumping system of claim 1, further comprising: a force transmitting element, wherein the force transmitting element is adapted for transmitting a driving power to at least one of the first pumping unit and the second pumping unit.
 5. The pumping system of one of claim 1, further comprising: a rod element; wherein the rod element is adapted for functionally coupling the first pumping unit and the second pumping unit such that a driving power, particularly a driving torque, is transmitted from the first pumping unit to the second pumping unit.
 6. The pumping system of one of claim 1, further comprising: an auxiliary conduit for conducting a fluid; wherein the auxiliary conduit is adapted for providing a fluid connection between a suction side and the first flow path.
 7. The pumping system of claim 6, wherein the first pumping unit is adapted to be supplied with fluid transported in the auxiliary conduit; wherein the second pumping unit is adapted to be supplied with fluid directly from the suction side.
 8. The pumping system of claim 6; wherein the auxiliary conduit is formed in an interior of the second pumping unit.
 9. The pumping system of claim 1, further comprising: an inner tubing; wherein the first pumping unit and the second pumping unit are located within the inner tubing; wherein the first pumping unit is located downstream the second pumping unit in a fluid pumping direction.
 10. The pumping system of claim 9, further comprising: an outer tubing; wherein the inner tubing is located within the outer tubing; wherein the inner tubing is spaced with respect to the outer tubing for providing a fluid drain there between.
 11. The pumping system of claim 10, wherein the fluid drain forms part of the first flow path or the second flow path.
 12. The pumping system of claim 9, further comprising: a barrier element; wherein the barrier element is located in the inner tubing between the first pumping unit and the second pumping unit; wherein the barrier element is adapted for separating the first flow path and the second flow path.
 13. The pumping system of claim 10, further comprising: a sealing spacer element; wherein the sealing spacer element is adapted for spacing the inner tubing and the outer tubing; wherein the sealing spacer element is adapted for preventing a flow of the fluid opposite to a fluid pumping direction in the fluid drain.
 14. The pumping system of one of claim 1, wherein the at least one progressive cavity pump particularly comprises a progressive cavity pump with a stator element and a rotor element adapted for rotating within the stator element with a distance between the stator element and the rotor element.
 15. The pumping system of claim 14, wherein the rotor element comprises a duct for providing a fluid connection between a suction side and at least one of the first flow path and the second flow path.
 16. The pumping system of claim 1, further comprising: a gear element; wherein the gear element is adapted for selectively driving exclusively one or both of the first pumping unit and the second driving unit.
 17. The pumping system of claim 1, wherein the first pumping unit and the second driving unit are located vertically on top of one another.
 18. The pumping system of claim 1, wherein the first flow path and the second flow path are parallel flow paths.
 19. A method for pumping fluid, wherein the method comprises: guiding fluid pumped by a first pumping unit through a first flow path; guiding fluid pumped by a second pumping unit through a second flow path; functionally coupling the first pumping unit and the second pumping unit; and providing the first flow path and the second flow path functionally independent from each other, wherein at least one of the first pumping unit and the second pumping unit comprises a progressive cavity pump.
 20. A method of using a pumping system of claim 1 in the field of one of the group consisting of drainage purposes, oil production, water catchment and geothermic systems. 